Skip to content

Commit

Permalink
Update Elo estimates for terms in search
Browse files Browse the repository at this point in the history 
based on 25k games per term, using the UHO_XXL_+0.90_+1.19.epd book, at STC.

More detailed information in the PR.

closes #4294

No functional change
  • Loading branch information
@FauziAkram @vondele
FauziAkram authored and vondele committed Dec 24, 2022
1 parent c620886 commit b2bd869
Showing 1 changed file with 24 additions and 24 deletions.
48 changes: 24 additions & 24 deletions src/search.cpp
View file
Expand Up @@ -633,16 +633,16 @@ namespace {
&& ttValue != VALUE_NONE // Possible in case of TT access race
&& (tte->bound() & (ttValue >= beta ? BOUND_LOWER : BOUND_UPPER)))
{
// If ttMove is quiet, update move sorting heuristics on TT hit (~1 Elo)
// If ttMove is quiet, update move sorting heuristics on TT hit (~2 Elo)
if (ttMove)
{
if (ttValue >= beta)
{
// Bonus for a quiet ttMove that fails high (~3 Elo)
// Bonus for a quiet ttMove that fails high (~2 Elo)
if (!ttCapture)
update_quiet_stats(pos, ss, ttMove, stat_bonus(depth));

// Extra penalty for early quiet moves of the previous ply (~0 Elo)
// Extra penalty for early quiet moves of the previous ply (~0 Elo on STC, ~2 Elo on LTC)
if ((ss-1)->moveCount <= 2 && !priorCapture)
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + 1));
}
Expand Down Expand Up @@ -734,7 +734,7 @@ namespace {
else // Fall back to (semi)classical complexity for TT hits, the NNUE complexity is lost
complexity = abs(ss->staticEval - pos.psq_eg_stm());

// ttValue can be used as a better position evaluation (~4 Elo)
// ttValue can be used as a better position evaluation (~7 Elo)
if ( ttValue != VALUE_NONE
&& (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)))
eval = ttValue;
Expand All @@ -750,7 +750,7 @@ namespace {

thisThread->complexityAverage.update(complexity);

// Use static evaluation difference to improve quiet move ordering (~3 Elo)
// Use static evaluation difference to improve quiet move ordering (~4 Elo)
if (is_ok((ss-1)->currentMove) && !(ss-1)->inCheck && !priorCapture)
{
int bonus = std::clamp(-19 * int((ss-1)->staticEval + ss->staticEval), -1914, 1914);
Expand All @@ -766,7 +766,7 @@ namespace {
: 168;
improving = improvement > 0;

// Step 7. Razoring.
// Step 7. Razoring (~1 Elo).
// If eval is really low check with qsearch if it can exceed alpha, if it can't,
// return a fail low.
if (eval < alpha - 369 - 254 * depth * depth)
Expand All @@ -776,7 +776,7 @@ namespace {
return value;
}

// Step 8. Futility pruning: child node (~25 Elo).
// Step 8. Futility pruning: child node (~40 Elo).
// The depth condition is important for mate finding.
if ( !ss->ttPv
&& depth < 8
Expand All @@ -785,7 +785,7 @@ namespace {
&& eval < 28031) // larger than VALUE_KNOWN_WIN, but smaller than TB wins
return eval;

// Step 9. Null move search with verification search (~22 Elo)
// Step 9. Null move search with verification search (~35 Elo)
if ( !PvNode
&& (ss-1)->currentMove != MOVE_NULL
&& (ss-1)->statScore < 17139
Expand Down Expand Up @@ -837,7 +837,7 @@ namespace {

probCutBeta = beta + 191 - 54 * improving;

// Step 10. ProbCut (~4 Elo)
// Step 10. ProbCut (~10 Elo)
// If we have a good enough capture and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move.
if ( !PvNode
Expand Down Expand Up @@ -888,7 +888,7 @@ namespace {
}

// Step 11. If the position is not in TT, decrease depth by 3.
// Use qsearch if depth is equal or below zero (~4 Elo)
// Use qsearch if depth is equal or below zero (~9 Elo)
if ( PvNode
&& !ttMove)
depth -= 3;
Expand All @@ -903,7 +903,7 @@ namespace {

moves_loop: // When in check, search starts here

// Step 12. A small Probcut idea, when we are in check (~0 Elo)
// Step 12. A small Probcut idea, when we are in check (~4 Elo)
probCutBeta = beta + 417;
if ( ss->inCheck
&& !PvNode
Expand Down Expand Up @@ -980,12 +980,12 @@ namespace {

Value delta = beta - alpha;

// Step 14. Pruning at shallow depth (~98 Elo). Depth conditions are important for mate finding.
// Step 14. Pruning at shallow depth (~120 Elo). Depth conditions are important for mate finding.
if ( !rootNode
&& pos.non_pawn_material(us)
&& bestValue > VALUE_TB_LOSS_IN_MAX_PLY)
{
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold (~7 Elo)
// Skip quiet moves if movecount exceeds our FutilityMoveCount threshold (~8 Elo)
moveCountPruning = moveCount >= futility_move_count(improving, depth);

// Reduced depth of the next LMR search
Expand All @@ -994,7 +994,7 @@ namespace {
if ( capture
|| givesCheck)
{
// Futility pruning for captures (~0 Elo)
// Futility pruning for captures (~2 Elo)
if ( !givesCheck
&& !PvNode
&& lmrDepth < 7
Expand All @@ -1003,7 +1003,7 @@ namespace {
+ captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] / 6 < alpha)
continue;

// SEE based pruning (~9 Elo)
// SEE based pruning (~11 Elo)
if (!pos.see_ge(move, Value(-222) * depth))
continue;
}
Expand All @@ -1020,23 +1020,23 @@ namespace {

history += 2 * thisThread->mainHistory[us][from_to(move)];

// Futility pruning: parent node (~9 Elo)
// Futility pruning: parent node (~13 Elo)
if ( !ss->inCheck
&& lmrDepth < 13
&& ss->staticEval + 106 + 145 * lmrDepth + history / 52 <= alpha)
continue;

// Prune moves with negative SEE (~3 Elo)
// Prune moves with negative SEE (~4 Elo)
if (!pos.see_ge(move, Value(-24 * lmrDepth * lmrDepth - 15 * lmrDepth)))
continue;
}
}

// Step 15. Extensions (~66 Elo)
// Step 15. Extensions (~100 Elo)
// We take care to not overdo to avoid search getting stuck.
if (ss->ply < thisThread->rootDepth * 2)
{
// Singular extension search (~58 Elo). If all moves but one fail low on a
// Singular extension search (~94 Elo). If all moves but one fail low on a
// search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
// then that move is singular and should be extended. To verify this we do
// a reduced search on all the other moves but the ttMove and if the
Expand Down Expand Up @@ -1095,7 +1095,7 @@ namespace {
&& abs(ss->staticEval) > 82)
extension = 1;

// Quiet ttMove extensions (~0 Elo)
// Quiet ttMove extensions (~1 Elo)
else if ( PvNode
&& move == ttMove
&& move == ss->killers[0]
Expand Down Expand Up @@ -1166,7 +1166,7 @@ namespace {
// Decrease/increase reduction for moves with a good/bad history (~30 Elo)
r -= ss->statScore / (13000 + 4152 * (depth > 7 && depth < 19));

// Step 17. Late moves reduction / extension (LMR, ~98 Elo)
// Step 17. Late moves reduction / extension (LMR, ~117 Elo)
// We use various heuristics for the sons of a node after the first son has
// been searched. In general we would like to reduce them, but there are many
// cases where we extend a son if it has good chances to be "interesting".
Expand Down Expand Up @@ -1462,7 +1462,7 @@ namespace {
if ((ss->staticEval = bestValue = tte->eval()) == VALUE_NONE)
ss->staticEval = bestValue = evaluate(pos);

// ttValue can be used as a better position evaluation (~7 Elo)
// ttValue can be used as a better position evaluation (~13 Elo)
if ( ttValue != VALUE_NONE
&& (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER)))
bestValue = ttValue;
Expand Down Expand Up @@ -1520,7 +1520,7 @@ namespace {

moveCount++;

// Futility pruning and moveCount pruning (~5 Elo)
// Futility pruning and moveCount pruning (~10 Elo)
if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY
&& !givesCheck
&& to_sq(move) != prevSq
Expand Down Expand Up @@ -1559,7 +1559,7 @@ namespace {
[pos.moved_piece(move)]
[to_sq(move)];

// Continuation history based pruning (~2 Elo)
// Continuation history based pruning (~3 Elo)
if ( !capture
&& bestValue > VALUE_TB_LOSS_IN_MAX_PLY
&& (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < 0
Expand Down

0 comments on commit b2bd869

Please sign in to comment.